The invention relates to a method for controlling the electrical charging of a group of vehicles and to a corresponding control system.
The prior art discloses the practice of controlling the charging of the energy stores of a group or pool of electrically drivable vehicles via a control system in such a manner that requirements of the operator of the power supply system used for charging with regard to a power reduction are also taken into account. In other words, in the case of a corresponding requirement of the power supply system operator, it is possible to interrupt or delay the charging of particular vehicles in the vehicle pool in order to thereby reduce the power consumption in the power supply system. In this case, the charging of only those vehicles in which the interruption in the charging operation does not influence a departure time specified by the user of the vehicle is suspended, that is to say there is still sufficient available time to charge the vehicle completely or to a predefined state of charge in the event of subsequent resumption of the charging operation.
During the above control of the charging of a vehicle pool, currently measured charging power measured values of the individual charging vehicles are taken into account in order to thereby ensure that a sufficient number of vehicles also suspend their charging operation, thus achieving the power reduction desired by the power supply system operator. However, the problem may arise in this case of particular charging power measured values being implausible since they exceed one or more predetermined maximum power measured values even though such exceeding could actually not occur. The use of implausible charging power measured values when controlling the charging of a vehicle pool may result, under certain circumstances, in the power reduction desired by the power supply system operator not being achieved.
Therefore, the object of the invention is to provide a method for controlling the electrical charging of a group of vehicles in such a manner that, even if implausible charging power measured values occur, the power reduction desired by a power supply system operator is achieved with a high degree of probability.
This and other objects are achieved by the method according to the invention for controlling the electrical charging of a group of vehicles which are electrically connected to a power supply system of a power supply system operator, wherein the respective vehicles draw power for charging a vehicle energy store for driving the respective vehicle from the power supply system. In other words, the vehicles are electrically drivable vehicles, for example pure electric vehicles or hybrid vehicles. In the method according to the invention, a central control system can communicate with the respective vehicles in the group and with a server of the power supply system operator. A central control system should be understood in this case as meaning a control system or a control device which controls the charging of all vehicles in the group. This control system is implemented, in particular, using software on a corresponding server. The central control system, in response to a received reduction command which comes from the server of the power supply system operator, controls a charging power reduction for the group of vehicles using charging power measured values of the respective vehicles. During this control, the central control system reduces the charging power of at least some of the vehicle energy stores. The charging of at least some of the vehicle energy stores is preferably suspended. This reduction in the charging power is intended to reduce the total charging power of the group of vehicles at least by a power value specified by the reduction command.
Within the scope of the method according to the invention, the charging power measured value of a respective vehicle is measured during the charging of the latter and is made available to the central control system. For example, the charging power measured value can be stored in a central store, for example a cloud store, and can then be retrieved by the control system. In one preferred variant, the charging power measured value is captured by a corresponding measuring device which is integrated, for example, in the charging station to which the respective vehicle is connected. In the method according to the invention, one or more maximum power values for charging the respective vehicle are also predefined and are not intended to be exceeded by the charging power measured value. In one preferred variant, the maximum power value(s) comprise(s) one or more of the following values and possibly also all of the following values:                a charging station maximum value which indicates the maximum charging power of the charging station at which the respective vehicle is charged;        a vehicle maximum value which indicates the maximum charging power of the respective vehicle;        a user maximum value which indicates a maximum charging power which can be configured by the user for the respective vehicle.        
The charging station maximum value is preferably the maximum physically possible charging power value for the charging station, but may possibly also be below this value. The vehicle maximum value is preferably the maximum physically possible charging power value of the corresponding vehicle, but may possibly also be below this value. The user maximum value is preferably not greater than the vehicle maximum value and preferably also not greater than the charging station maximum value. The charging station maximum value is preferably above the vehicle maximum value or is the same as the vehicle maximum value.
The method according to the invention is distinguished by the fact that, if the charging power measured value of the respective vehicle exceeds the minimum value of all maximum power values and charging power reduction control is imminent, the central control system uses a replacement value, which is the minimum value of all maximum power values, instead of the measured charging power measured value to control the charging power reduction when it occurs. Otherwise, that is to say if the charging power measured value of the respective vehicle does not exceed the minimum value of all maximum power values and charging power reduction control is imminent, the central control system uses the measured charging power measured value to control the charging power reduction.
In the method according to the invention, use is made of the knowledge that an implausible charging power measured value should be set as low as possible before the start of the corresponding charging power reduction control in order to avoid a charging power measured value which is incorrectly assumed to be too high from resulting in the power not being sufficiently reduced according to the reduction command of the power supply system operator.
In one preferred embodiment of the method according to the invention, the scenario is also considered in which an implausible charging power measured value occurs during charging power reduction control which is currently being carried out, for example at the time at which the corresponding vehicle is connected to a charging station. In this variant, the maximum power values comprise the charging station maximum value, the vehicle maximum value and the user maximum value. In this case, if the charging power measured value of the respective vehicle exceeds the minimum value of the charging station maximum value and the vehicle maximum value, the central control system uses a replacement value, which is the minimum value of the charging station maximum value and the vehicle maximum value, instead of the measured charging power measured value to control the current charging power reduction. Otherwise, that is to say if the charging power measured value of the respective vehicle does not exceed the minimum value of the charging station maximum value and the vehicle maximum value during charging power reduction control which is currently being carried out, the central control system uses the measured charging power measured value to control the charging power reduction. In this embodiment, use is made of the knowledge that, on account of the configurability of the user maximum value, the vehicle maximum value or the charging station maximum value is present with a higher degree of probability than the user maximum value in the case of implausible measured values. It is also taken into account that a charging power measured value which is incorrectly assumed to be too low during charging power reduction control which is currently being carried out can result in the charging power of other vehicles not being reduced enough and the requirements according to the reduction command of the power supply system operator therefore not being achieved.
In another particularly preferred embodiment, the central control system can also process corresponding increase commands of the power supply system operator. In other words, in response to a received increase command which comes from the server of the power supply system operator, the central control system controls a charging power increase for the group of vehicles using the charging power measured values of the respective vehicles. During this charging power increase control, the control system increases the charging power of at least some of the vehicle energy stores in order to increase the total charging power of the group of vehicles at least by a power value specified by the increase command. Implausible charging power measured values are also preferably suitably processed in the case of such an increase command in order to ensure to the greatest possible extent that the charging power is increased according to the increase command.
In one variant of the method according to the invention, if the charging power measured value of the respective vehicle exceeds the minimum value of all maximum power values and charging power increase control is currently being carried out, the central control system uses a replacement value, which is the minimum value of all maximum power values, instead of the measured charging power measured value to control the current charging power increase. Otherwise, that is to say if the charging power measured value of the respective vehicle does not exceed the minimum value of all maximum power values and charging power increase control is currently being carried out, the central control system uses the measured charging power measured value to control the charging power increase. This embodiment takes into account the fact that a charging power measured value which is incorrectly assumed to be too high can result, during ongoing charging power increase control, in sufficient power no longer being provided by other vehicles in order to achieve the power value according to the increase command.
In another variant, if the charging power measured value of the respective vehicle exceeds the minimum value of the charging station maximum value and the vehicle maximum value and charging power increase control is imminent, the central control system uses a replacement value, which is the minimum value of the charging station maximum value and the vehicle maximum value, instead of the measured charging power measured value to control the charging power increase when it occurs. Otherwise, that is to say if the charging power measured value of the respective vehicle does not exceed the minimum value of the charging station maximum value and the vehicle maximum value and charging power increase control is imminent, the central control system uses the measured charging power measured value to control the charging power increase. In this variant, the maximum power values comprise the charging station maximum value, the vehicle maximum value and the user maximum value. In this case, it is taken into account that the charging station maximum value or the vehicle maximum value is present with a higher degree of probability than the configurable user maximum value. It is also taken into account that a charging power measured value which is incorrectly set to be too low can result, before the start of charging power increase control, in the power of other vehicles no longer being sufficiently increased, when increasing the charging power of the corresponding vehicle at the start of the power increase control, to achieve the power increase according to the increase command.
In another variant of the method according to the invention, when controlling the charging power reduction and/or the charging power increase, the central control system corrects the charging power measured value or replacement value used in the process on the basis of a degradation function which describes a decrease in the charging power of the vehicle energy store as the fully charged state is approached. In this manner, the charging power measured value or the replacement value is set more accurately on the basis of the state of charge of the energy store.
In addition to the method described above, the invention relates to a central control system for controlling the electrical charging of a group of vehicles which are electrically connected to a power supply system of a power supply system operator, wherein the respective vehicles draw power for charging a vehicle energy store for driving the respective vehicle from the power supply system. The central control system can communicate with the respective vehicles in the group and with a server of the power supply system operator, wherein the central control system is set up, in response to a received reduction command which comes from the server of the power supply system operator, to control a charging power reduction for the group of vehicles using charging power measured values of the respective vehicles and in the process to reduce the charging power of at least some of the vehicle energy stores in order to reduce the total charging power of the group of vehicles at least by a power value specified by the reduction command. In this case, the central control system is set up to carry out a method in which:                the charging power measured value of a respective vehicle which is measured during the charging of the latter is made available to the central control system, wherein one or more maximum power values for charging the respective vehicle are also predefined and are not intended to be exceeded by the charging power measured value;        if the charging power measured value of the respective vehicle exceeds the minimum value of all maximum power values and charging power reduction control is imminent, the central control system uses a replacement value, which is the minimum value of all maximum power values, instead of the measured charging power measured value to control the charging power reduction, wherein, if the charging power measured value of the respective vehicle does not exceed the minimum value of all maximum power values and charging power reduction control is imminent, the central control system uses the measured charging power measured value to control the charging power reduction.        
The control system just described is preferably configured in such a manner that it can carry out one or more preferred variants of the method according to the invention.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.